The focus of this proposal is the development of a novel in-vivo imaging device (Molecular Breast Imaging system) that incorporates a clinical validation experiment and a limited pilot and a clinical feasibility evaluation for pre-clinical and clinical studies. Our primary intent is to facilitate the proof of feasibility of this novel imaging device for early detection, diagnosis, and treatment monitoring of breast cancer. The purpose of this imaging system is to define the characteristics of breast cancer at a molecular level using both established and novel radioactive markers that can enable the early detection and monitor the treatment of breast cancer. The novelty of this system is two fold: 1) development of a system that will comprise two opposing Cadmium Zinc Telluride (CZT) semi-conductor detectors in a specialized gantry, and 2) development of algorithms and corresponding clinical software packages that will permit absolute quantitation of tumor uptake of radiopharmaceuticals and permit monitoring of the kinetics of uptake and washout of radiopharmaceuticals in breast tissue. It is our primary goal in this Fast Track STTR proposal to create clinical tools, dual-headed breast imaging system (to be developed by GM) and software for quantitative analysis of the image data (Mayo) for functional breast imaging. Our secondary goal is demonstrate the ability of the camera to be utilized as a preclinical research device. Each facility will complete small patient trials to illustrate the potential application of this device and associated software in the evaluation of new radiopharmaceuticals for detection of breast cancer. During the Phase I of this Fast Track STTR we will construct a fully functional Dual Headed CZT breast imaging camera complete with Acquisition, Processing, Tumor Quantification, and simultaneous dual Isotope Capabilities. One tested prototype camera will be built during Phase-I and two additional cameras will emulate the original and their assembly will take place during Phase-II. During Phase-II of this proposal the primary goal is to evaluate the clinically usefulness of a dual-headed breast imaging system (to be developed by GM) and software for quantitative analysis of the image data (to be developed by Mayo). This will be accomplished through a multi-center pilot study. Three sites will conduct a patient study that will validate the ability of this device to detect sub-10 mm breast lesions. The secondary goals are 1) to compare the diagnostic capabilities of this device to MRI, 2) to explore the potential application of this device in dual-isotope studies, and 3) to demonstrate its ability to evaluate new promising radiopharmaceuticals. The secondary goals will be accomplished during Phase II and will be undertaken at all three clinical sites. [unreadable] [unreadable] [unreadable]